Embodiments of the invention are directed to wireless communication devices, and more specifically, to improving the efficiency of portable wireless communication devices used in a variety of situations, such as mobile telephones paired with mono or stereo Bluetooth headsets, or portable computers paired with mono or stereo Bluetooth headsets.
For many such devices, the power required for transmitting and receiving data over the transceiver (or radio) is a substantial and significant proportion of the overall system power consumption. Inefficiency in the transceiver performance can lead to overall system inefficiency, resulting in user dissatisfaction, poor battery life, poor quality reception or transmission, or larger and more costly devices due to larger and more expensive batteries.
There are many existing systems used to optimize transceiver communications, including Yagi antennas, directional antennas, diversity systems, monopole and dipole antennas, planar patch antennas, and so forth. Some of these have radiation patterns that are broadly omni-directional (that is, the intensity of radiation produced by or detected by the antenna at a given distance from the antenna is approximately the same in all directions), whereas some are strongly directional (that is, the intensity of radiation at a given distance is much higher in some directions relative to the antenna than in others).
Designers of systems in which antennas are utilized are often careful to ensure that the radiation pattern for their antenna is appropriate for the typical usage or use cases of a device. For example, in a mobile phone, the antenna and associated components are designed so that the radiation pattern is typically such that little radiation is directed towards the user's head when they are holding the phone in a manner typical of making a phone call, as radiation directed to the head is absorbed by the head; therefore, this represents an inefficient direction to orient radiation and hence transmit voice communications or data. This arrangement may also be used in order to reduce the amount of energy absorbed by the head for health reasons. As another example, the manufacturer of a Bluetooth headset might choose to design an antenna with a radiation pattern that is optimal for communicating with a mobile phone in a user's pocket or purse.
A disadvantage of such a design methodology is that such designs can be highly non-optimal in other common situations of use. For example, consider a mobile phone with a radiation pattern optimized as above for use when the user is holding the mobile phone to his or her ear. For such a mobile phone, consider the case where the user has the mobile phone in a pocket, with the outward face when held to the ear now inward-facing in the pocket. In this configuration, the radiation direction with the strongest intensity is oriented towards the user's body and will be absorbed, while the direction away from the body is the direction with the weakest intensity. Such a mobile phone position or orientation is very inefficient with regard to voice or data transmission and may consume substantially more power than would otherwise be needed.
Another design strategy that may be employed is to utilize an omni-directional radiation pattern, as such a pattern will typically not have such a disadvantage. However, such a design tradeoff means that the transceiver is less efficient in the “normal” or typical use case, and will in general be of non-optimal efficiency in other usage cases.
As recognized by the inventor, it is desirable that the radiation pattern of an antenna that is part of a headset, handset, or other device be variable based on the different usage scenarios or device configurations in which the device may be used, for purposes such as voice communication and/or data transmission. Such a variable pattern would have multiple benefits, including, but not limited to, improving battery life, reducing size and cost, and improving the quality of voice or data transmission and reception. Embodiments of the invention address these problems and other problems individually and collectively.